TITLE: Where can I find Linear Algebra in Nature?
QUESTION [8 upvotes]: I'm a Computer Science major and I've been studying Analytic Geometry and Linear Algebra this semester. Today my teacher gave a hell of an explanation talking about linear systems, quadratic functions, polynomial equations, derivatives, etc., etc.. In his examples, he talked about Ballistics, about space and all matter, about the physical "tissue" that covers every object, cars and its aerodynamics, and so on and I was basically tripping with so many crazy ideas.
I really, really loved this subject and have even been considering studying it more out of the Academia for curiosity purposes. 
The thing is, I couldn't find more of these examples where linear algebra can be used in nature. I know about some possible uses in Computer Science such as Computer Graphics, A.I., cryptography and etc..
Can anyone shed a light?
Thanks!

REPLY [2 votes]: A short description of Quantum Information Theory is the study of unitary and related operators on tensor products of Hilbert spaces (complete inner product spaces).  This is not, as Scott Carter incorrectly indicates in the comments, because quantum mechanics is just a linear approximation.  (It is true that the standard model of quantum field theory isn't rigorously understood in a nonperturbative sense, but that is a problem of mathematical analysis not related to the basic framework for all such theories as postulated by the Wightman axioms.)  A good introduction to this subject is John Preskill's course notes from the quantum computation class at Caltech.  (Just do a google search for preskill notes physics 219 if you're interested.)